The subway stations - bridge unitized (station - bridge unitized) projects can reduce urban traffic congestion and save construction space. But their seismic response mechanism and the seismic response of underground structures are not very clear. The three-dimensional model of station - bridge unitized condition and single station condition were established using finite difference software. Firstly, static calculations were completed, and the law of force and deformation of two conditions were analyzed. On the basis, with the input of El-Centro and Kobe waves, interlayer displacement angle, stress and weak positions of subway station were analyzed. Finally, the effects of load and height of the bridge on the seismic response of subway station were studied. The results indicate that as the input acceleration of bedrock increases, the effect of the overpass on the interlayer displacement angle and maximum stress of the subway station becomes greater. The middle column is the weak position of two conditions. However, the tensile Tensile damage at the ends of station roof floors is easier to occur in station - bridge unitized condition, and the middle columns should also be attached importance to in strong earthquake. The influence of bridge loads on the seismic response of station is more significant than that of the bridge height. There is a positive linear correlation between the interlayer displacement angle and bridge load, which can also be seen in bridge height. And stresses increase linearly with bridge load and height.tance to in strong earthquake. The influence of bridge loads on the seismic response of station is more significant than that of the bridge height. There is a positive